1. Field of the Invention
The present invention pertains to visual bore hole logging. The visual examination of the bore hole for casing damage and/or fracturing and sediment stratification may be made with a video camera lowered throughout the bore hole and a video monitor in conjunction with a video cassette recorder for visualizing and recording the wall of the bore hole.
2. Description of the Prior Art
A well or bore hole is an artificial excavation made to extract water, oil, gas, and other substances from the earth. There is also the boring and drilling of holes for exploration. Exploration holes are drilled to locate mineral deposits such as oil and gas, ground water, geothermal supplies, to check for the integrity for nuclear waste depositories, and also to determine potential landslides in an unstable environment. Closed circuit TV camera systems are known in the art for visually examining the walls of a given bore hole. Additionally, in large diameter bore holes, a trained geologist can be physically lowered into the hole with a light source to visually examine the stratification, fracturing and layering of the various geological formations down through which the bore hole penetrates. In small diameter holes, this type of examination is impossible. Accordingly, in smaller diameter holes visual wall examination must be made with a moving picture bore hole camera or with a closed circuit television video camera. Furthermore, the heat, vapors, and fluids encountered in many bore holes make it dangerous for a trained geologist to be lowered down into the hole regardless of the diameter of the bore hole. In these types of bore holes, the geologist cannot be used, and the down hole video camera and tool must be employed.
Additionally, the bore shaft itself made by the bore hole is often not in a vertical orientation and has a drift or deviation in azimuth from its true vertical. There are drift recorders which monitor and log the slanting or drifting of the bore hole from its true azimuth. Inclinometers are known which determine deviation as well as drift, for example, by photographing from a plumb bob position against a compass background.
Additionally, while in the process of drilling a well and/or installing the steel tubing or casing to reinforce the wall of the bore hole, occasionally because of cave-ins, sedimentation and the like, the equipment in the hole becomes lodged and stuck therein. It then becomes a matter of locating the stuck pipe or other equipment in the wells. U.S. Pat. No. 2,817,808 issued to Giske, describes a method and apparatus for locating stuck pipe in wells.
After the steel casing or tubing has been in place for sometime in a well such as a ground water well, rusting and other shifts in the earth occasionally will cause rupturing or uncoupling of the steel casing. In this event, visual examination of the casing is necessary to see the extent of the break or leak and the feasibility of repairs.
Accordingly, the visual examination of the walls of a well are frequently needed when applied to the above problems.